Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds the endpoint call to /trains/getRoute and specifies the input is a known train number, but it does not disclose additional behavioral details such as pagination, availability windows, or partial route responses.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences, front-loaded with the core use case and a short endpoint reference. Every word earns its place and there is no extraneous content.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

This is a simple one-parameter, read-only tool with an output schema provided and accurate annotations. The description fully explains the scope (complete route and stoppages by known train number), so no additional context is needed for the agent to invoke it appropriately.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and the single train_number parameter is described as a 5-digit train number. The description adds no additional semantic information beyond reaffirming "known train number," so the baseline of 3 is appropriate since the schema carries the burden.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states the tool provides "complete route and stoppage details of a known train number," which is a specific and clear purpose. This distinguishes it from sibling tools like live status or PNR status by focusing on full route/stoppage data.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It explicitly says "Use this tool for..." when route and stoppage details are needed for a known train number. It does not mention alternatives or exclusions, but the context is clear enough for the agent to choose it among siblings.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.